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[221.241.217.81]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-77cfe7607c8sm16949307b3a.58.2025.09.23.16.51.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Sep 2025 16:51:54 -0700 (PDT) Date: Wed, 24 Sep 2025 08:51:50 +0900 Message-ID: From: Hajime Tazaki To: johannes@sipsolutions.net Cc: geert@linux-m68k.org, linux-um@lists.infradead.org, ricarkol@google.com, Liam.Howlett@oracle.com, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: [PATCH RESEND v11 10/13] um: nommu: a work around for MMU dependency to PCI driver In-Reply-To: <23adb61e95275251e459513a03ab7d2bcf1f2e07.camel@sipsolutions.net> References: <4a9dde10c586883d20a8201ca7d76e6d7d52eaf4.1758181109.git.thehajime@gmail.com> <6b1abe384237c8129e8043ecdfdad77758d2fd2f.camel@sipsolutions.net> <23adb61e95275251e459513a03ab7d2bcf1f2e07.camel@sipsolutions.net> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/27.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII Hello Geert, Johannes, On Wed, 24 Sep 2025 02:13:47 +0900, Johannes Berg wrote: > > On Tue, 2025-09-23 at 17:42 +0200, Geert Uytterhoeven wrote: > > > > > > currently, drivers/pci/Kconfig (CONFIG_PCI) marks as depends on MMU, > > > so we cannot select it when CONFIG_MMU=n. > > > > That is a fairly recent change, see commit 8fe743b5eba0abfb ("PCI: > > Add CONFIG_MMU dependency") in v6.16-rc1. As this is not a "hard" > > dependency, perhaps it should be reverted, iff you are willing to take > > care of the casual breakage? > > Why though? UML with PCI can't really be a functional thing, only a > testing thing, and testing PCI on !MMU when that is actually impossible > in non-simulation is pointless? currently nommu UML doesn't come with using PCI except building under kunit (ARCH=um), but I have in my mind to use it under !MMU environment, so would be an option in the future. and this series doesn't include PCI w/ !MMU. so, I would propose the modification to revert the MMU dependency when time has come. btw, what do you mean by "hard" dependency in this context, Geert ? -- Hajime